Restraint chain storage

ABSTRACT

A temporary barrier chain for a loading dock door opening includes a vertical orientated storage tube on one side of the opening and a retainer on the other side thereof, and a counterweighted chain extending from inside the storage tube to a retainer on the other side of the opening, with the chain being comprised, at least partially, of successively lighter weight sections toward the retainer end such that the combined weight of the counterweight and suspended chain within the storage tube will cause the chain to be automatically retrieved into the storage tube when released from the retainer.

TECHNICAL FIELD

This invention relates generally to restraint barriers and, more particularly, to an apparatus for retracting and storing a restraint chain when not in use.

For purposes of safety and possibly other reasons, it has been desirable to temporarily close off an area from entry or exit with a barrier such as a belt or chain being strung across an opening to temporarily close it off but later allow the belt or chain to be removed and stored in a housing to clear the opening for entry or exit. An example of such a device is a belt which has traditionally been used at the door opening of a warehouse dock. Although the safest approach is to have a solid door that is open only at times when the truck is backed-up to the opening and closed at all other times, there are occasions when this is not practical, such when there is a need for ventilation in the warehouse, for example. Thus, a belt across the opening provides a visual indication that the space is not open for use and that caution should be taken when one is in that vicinity. Provision is then made for selectively retracting the belt by way of spring loaded mechanism to remove the strap from the vicinity of the opening. Such an apparatus is described in U.S. patent application Ser. No. 11/471,803, filed on Jun. 21, 2006 and assigned to the assignee of the present application.

A disadvantage to such a retraction system is the complexity and cost. Further, although the belt is normally designed to withstand a force such as might be experienced when struck by a person, for example, there are some installations where a greater robustness is desired so as to assure the user that the strength of the barrier will not be exceeded and that it will remain durable for long periods of use. This additional strength and durability can be obtained by the use of a steel chain. However, such a chain cannot easily be wound up or retracted by way of a spring loaded mechanism.

One approach to solving the chain storage problem is to provide a counterweight on the storage end of the chain such that the free fall of the counterweight will act to retract the chain into a tube. However, in order to accomplish this, it is necessary to have a cavity of substantial depth under the floor in order to accommodate the free fall of the counterweight.

There is therefore a need for a method and apparatus for retracting and storing a restraint chain without the need for a cavity under the floor.

DISCLOSURE OF THE INVENTION

Briefly, in accordance with one aspect of the invention, the barrier chain comprises a plurality of interconnected sections which are progressively smaller as they extend away from counterweight such that the weight of the chain exerting gravitational pull within the storage trunk is greater than the weight of the extended chain from the mouth of the storage trunk to the floor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the present invention as installed in a loading dock door opening.

FIG. 2 is a perspective view of the chain and storage portion thereof.

FIG. 3 is an exploded view of the chain portion thereof.

FIG. 4 is a perspective view of the chain portion as placed in the stored position.

DETAILED DESCRIPTION OF THE INVENTION

The invention is shown generally at 10 as applied to an opening 11 in a loading dock 12 when a door is in the open position. Its purpose is two fold: that of providing an indication to people in the vicinity that they should be aware of the open door condition and secondly, to act as a barrier to people that may be in the vicinity.

The invention 10 includes a chain 13 which extends across the opening 11, a retainer bracket 14 secured to the wall 16 on one side of the opening 11, and a storage tube 17 secured to the wall 18 on the other side of the opening 11. The storage tube 17 is designed to store the chain 13 in its inner space during periods in which the chain is not in use. To extend the chain as shown, the chain is simply pulled out of the storage tube 17 with its one end being mechanically secured in the retainer bracket 14 as shown. The chain 13 is so sized and placed that the center of the sag is 42-48 inches above the top surface of the loading dock 12. Thus, the chain 13 is generally about 10 feet long, with the two ends thereof being at about 51 inches above the top surface of the loading dock 12. It should also be of sufficient strength to sustain a force of 300 pounds.

Referring now to FIG. 2, the storage tube 17 is shown to include three serially and integrally connected portions including, a straight portion 19, a 90° elbow 21, and a bell 22 with an orifice 25. The inside diameter of those members is 2.25 inches. However, that size can be varied to accommodate the particular installation, keeping in mind that the storage tube 17 must be of sufficient strength to maintain its vertical position for years of use without being bent over or broken. Further, it must be of a size to accommodate the storage of all of the chain in a manner as described hereinafter. The storage tube 17 is preferably made of a steel material, but other suitable materials may also be used.

At the base of the straight portion 19 is an L-shaped bottom bracket 23 that is used to attach the storage tube 17 to the wall and/or the floor. A top bracket 24 surrounds a top portion of the straight portion 19 and is used for attachment of a top portion of the storage tube 17 to the wall. In this way, a storage tube 17 can be located entirely above the floor, and can therefore be installed in an existing warehouse without disturbing the floor. Alternatively, if installed in a building under construction, it may be constructed so as to extend into the floor for stability purposes, and if so, either the bottom bracket 23 and/or top bracket 24 may be omitted.

The bell portion 22 provides for an expanded diameter as it extends away from the elbow 21. It is desirable for facilitating the easier return of the chain 13 to the storage tube 17 when the chain is being stored.

A bolt 26 is passed through the straight portion 19 near its upper end after the counterweight has been installed in the storage tube 17 so as to retain the counterweight 27 within the storage tube 17. This function can also be performed by “necking down” the tube at the appropriate position and then inserting the counterweight from the bottom of the tube during the installation phase.

The chain 13 and its attached counterweight 27 is shown in exploded view in FIG. 3. The counterweight 27 is of any suitable shape, such as a cylindrical shape as shown, and is of a weight which will cause the chain to be retrieved when the counterweight 27 descends to the bottom of the storage tube 17. The particular one shown is about 4-5 inches tall, 2.25 inches in diameter and weighs about 5 pounds. It is secured to the first section 28 of the chain 13.

The chain is comprised of five sections 28, 29, 31, 32 and 33, with interconnecting S hooks 34, 36, 37 and 38 as shown. As will be seen, the section 28 and the section 31 are comprised of the same type of chain (i.e. 5/16 inch steel chain), and the section 29 is comprised of a lighter weight chain that merely serves to connect the sections 28 and 31 but plays no active role in the weighting algorithm in order to allow for automatic retrieval of the chain 13. However, it will also be seen that the section 31, 32 and 33 are of decreasing weight such that, once the counterweight falls to the bottom of the storage tube 17, the weight of the chain suspended from the top of the storage tube (i.e. from the bell 22 to the pile of chain piled at the bottom of the storage tube 17 is sufficient to cause, by its gravitational pull, the remaining portion of the chain 13 to be drawn into the storage tube 17.

A description of each section of the chain 13 is shown in Table 1 below.

TABLE 1 Section Type # of Lines Length Weight 28 5/16 steel welded 10 13.32 in. 1.32 lb. 29 2/0 twist machine 23 18 in. 13 lb. 31 5/16 steel welded 12 15.88 in. 1.45 lb. 32 2/0 twist machine 48 35 in. .9 lb. 33 #3 twist machine 60 36 in. .4 lb.

Thus, considering that the distance from the bottom of the storage tube 17 to the center of the bell 22 is 52 inches, when the counterweight 27 reaches the bottom of the storage tube 17 the sections 28 and 29, as well as substantially all of the section 31, will be extended between the counterweight 27 and bell 22. Thus, the weight of the section 31 will exceed the weight of those sections 32 and 33 combined, and its gravitational pull will cause the sections 32 and 33 to be drawn into the bell 22. As the section 31 falls downwardly and tends to pile up on the chain sections below, its gravitational pull is gradually reduced, but at the same time, there are portions of the section 32 which have now been drawn into the storage tube 17 and which are acting to further pull the chain into the storage tube 17. In this way, with the aid of the counterweight 27 and the weight of the suspended chain within the storage tube 17, there is a constant bias for the chain 13 to be automatically retrieved once it is disconnected from the bracket 14.

Connection of the chain 13 to the bracket 14 is by way of a T-clip 39 which is attached to the section 33 by way of connecting link 41.

The chain 13 is shown in the fully retrieved condition in FIG. 4 wherein the T-clip 39 is against the bell 22. When it is desired to again extend the chain across the opening, one simply needs to pull the T-clip and the attached chain to the extended position and again attach the T-clip to the bracket 14.

While the present invention has been particularly shown and described with reference to the preferred mode as illustrated in the drawing, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the invention as defined by the claims. 

1. A restraint barrier apparatus comprising: a chain having sufficient length and strength to be selectively either extended across an opening and temporarily attached at its one end to one side of the opening so as to provide a barrier across the opening, or retracted to the other side of the opening; a storage tube disposed on the other side of the opening, said tube having an orifice near a top end for said chain to extend therethrough, said tube being substantially and entirely above a floor level and being of sufficient height and width to contain the entire length of said chain; a counterweight attached to the other end of said chain, said counterweight being disposed within said storage tube at an elevated position when said chain is extended and adapted to fall by gravity to the bottom of said trunk when said chain is to be retracted; wherein, said chain is at least partially composed of a plurality of sections of decreasing weight toward said chain one end such that, as said chain is automatically retracted into said trunk by the combined weight of the counterweight and the chain, the weight of the chain portion extending from the orifice to a pile of chain at the bottom of the trunk exceeds the weight of the unretracted chain extending outside of the orifice.
 2. A restraint barrier apparatus as set forth in claim 1 wherein said chain is comprised of a steel material.
 3. A restraint barrier apparatus as set forth in claim 1 wherein the height of said storage trunk orifice is about 51 inches above the floor.
 4. A restraint barrier apparatus as set forth in claim 1 wherein the length of said chain is about 10 feet long and comprises 5 sections.
 5. A restraint barrier apparatus as set forth in claim 1 and including an aluminum clip at said chain one end.
 6. A restraint barrier apparatus as set forth in claim 1 and including a restraint member near a top end of said trunk to prevent said counterweight from being withdrawn from said truck after being installed therein.
 7. A restraint barrier apparatus as set forth in claim 1 wherein said storage tube is cylindrical in form.
 8. A restraint barrier apparatus as set forth in claim 1 and including an elbow near said storage tube top end.
 9. A restraint barrier apparatus as set forth in claim 1 and including a bell shaped portion at said orifice with said bell shaped portion being of increased diameter as it extends away from said storage tube.
 10. A temporary barrier for a loading dock door opening, comprising: a storage tube disposed on one side of the door opening and extending upwardly from the floor to an upper opening so as to provide an internal space for storage; a barrier chain being of a length to extend across said opening when secured at its ends to either side of the opening; a counterweight attached to one end of said chain and being vertically moveable within said storage tube; and an attachment member on the other end of said chain for attachment to a retainer on the other side of the door opening; wherein said chain is of a length and weight and at least partially comprised of successively lighter weight sections as it extends away from said counterweight, such that when said attachment member is disconnected from said retainer, the force of gravity acts on the counterweight and chain within said storage tube to automatically cause the entire chain to be retrieved into said storage tube.
 11. A temporary barrier as set forth in claim 10 wherein said storage tube is cylindrical in form.
 12. A temporary barrier as set forth in claim 10 and including an elbow near said storage tube upper opening.
 13. A temporary barrier as set forth in claim 10 and including a bell shaped portion at said upper opening, said bell shaped portion being of increased diameter as it extends away from said storage tube.
 14. A temporary barrier as set forth in 10 and including a restraint member in said storage tube at a point near said upper opening so as to retain said counterweight within said storage tube.
 15. A temporary barrier as set forth in claim 10 wherein said storage tube is about 51 inches in length. 